Topic: Why is my master account being treated as a sub account?

Yesterday I bought a pre-paid 12-month playstation plus membership from a store. I took the card home and activated it and it worked fine, the code was accepted for a 12-month membership, the only problem is as I pressed the last 'confirm' button I got a message on my screen saying "An error has occured. WC-40355-7". After looking that code up on the playstation website I found that the code means you cant buy/purchase anything on a sub-account, because apparently they do not have wallets. The problem is, my account has always been a master account and has never been a sub account. I have always been able to purchase things off the store, share to facebook and this is not the first 12-month playstation plus pre-paid card I have bought before. Furthermore, I can still do all of these things, I am still able to share to other networks and my account is not connected to any master account. The only thing I cannot do is activate this 12 month membership. I've checked all of my information (adress, name etc) and it's still all correct. Does anyone know why this is happening, did I miss something pretty important? Thankyou.

I would try contacting Sony. It sounds like their might be a problem with the card.